1. Field of the Invention
The present invention relates to a computer system in which a number of individual computers are interconnected by means of a system bus, and more particularly to apparatus for improving the efficiency of communication between the system bus and the individual computers.
2. The Prior Art
A computer system of the type having a number of individual computers interconnected by means of a system bus has been described in copending application of Rudolf Kober et al. U.S. Ser. No. 732,988, filed Oct. 15, 1976. In a computer system of the kind described in that application, the entire data traffic between the individual computers takes place by way of the system bus. Each of the individual computers has a read-write memory serving as the coupling link between that computer and the system bus. During operation of the system, data is transmitted by way of the system bus and the associated addresses by way of the system address bus. The data exchange between the individual computers and the system bus is performed by the read-write memory associated with each of the individual computers. Typically, data which is intended for one of the individual computers is entered into the read-write memories of all of the individual computers.
A central control computer establishes a data path which reads from a selected read-write memory of one of the individual computers to the read-write memories of all of the other individual computers. This operation is repeated for data generated by any of the individual computers. It therefore follows that all of the read-write memories contain at many times the same data, even if only one or a few of the individual computers need such data. For many specific computer operations, the proportion of the data required by any individual computer is relatively small. When, as in the past, the read-write memories of the individual computers have sufficient capacity to maintain in storage all of the data transmitted over the system bus, a relatively large capacity for each of the read-write memories is required. It is desirable to provide apparatus for making it possible to reduce the required capacity of the read-write memories associated with the individual computers.